What a fascinating story!
I don't think there's any connection between the Marston-Holloway-Byrne triad and Hubbard, and I don't think Hubbard would have liked Marston's ideas.
(1) Marston thought of people, their thoughts and emotions, as the interaction of fundamentally biological factors with their environment. During a period when spiritualism and mysticism were sometimes being dragged into discussions of psychology, he stuck with (nascent) neurology. It wasn't yet an advanced enough science to give his ideas a solid foundation, but he gave it a good try with what was available.
(2) The enduring and seemingly happy polyamorous triad they had was pretty amazing for the time, and aspects of it really make me think of third wave feminism, when the first wave was still going on (Olive's aunt was Margaret Sanger, and Olive's mother was very active in the same cause). Ron, on the other hand, wrote a wedding ceremony where he refers to the bride in simple, childlike terms: "Girls need clothes and food and tender happiness and frills, a pan, a comb, perhaps a cat. All caprice if you will, but still they need them." I also don't recall anything he wrote where a heroine was the protagonist, he stuck to pretty traditional sexist stereotypes. His three marriages, overall, don't look remotely egalitarian, and the Admissions contain entries which come across as misogynistic, to put it mildly.
Marston believed that women were as capable of being socially dominant as men were, and was married to a Harvard educated psychologist and lawyer, who had a real career. Olive got as least as far as working on her doctorate, at a time when many universities would not accept women into their doctoral programs. And Olive was married to both of them, not just Mr. Marston.
Heinlein might have smiled on such a thing, but not Hubbard. Per Science of Survival, both wives would have been covertly hostile, the relationship(s) should have been a disaster, and the whole arrangement would have been considered wildly out 2D. Krafft-Ebing regarded non-reproductive forms of sex as perverse, and Hubbard personally rejected that idea in his Admissions, while publicly mostly going along with it. I see no such conflicts in Marston, aside from his household's need to keep the nature of their relationships private. They were solidly in the camp of Havelock Ellis, who had coincidentally had an affair with Olive's aunt Margaret.
So no, I don't think there's any link there, but if I try to imagine a Hubbard who was inspired by Marston, I think he would have been the better for it.